The invention relates to a headlight lantern system comprising at least two pairs of lanterns, or headlamps, adapted to be mounted in the front part of an automobile with one lantern of each pair on either side of the center of this front part. The lanterns of one pair each during operation produce a dipped, or low, beam and the lanterns of the other pair each produce, a main or high, beam. The headlamps have a concave flattened reflector having an optical axis and a focus and a quadrangular pane closing the reflector. The pane has an average height dimension smaller than 60 mm and an average width dimension, the ratio of the average width dimension to the average height dimension being larger than 3.
A respective electric light source is axially arranged in each of the lanterns and is surrounded by a translucent envelope filled with gas and sealed onto the current supply conductors. The invention further relates to an electric lamp suitable for use in this headlight lantern system.
Such a headlight lantern system is known from GB No. 2 154 726 which corresponds to U.S. Pat. No. 4,760,501.
In the known headlight lantern system, high-pressure gas discharge lamps are used as light sources. Such lamps have the advantage over the usual incandescent lamps for cars, inclusive of halogen lamps for cars, that the light source has a very high degree of brightness. As a result, it is possible to use lanterns having reflectors with a comparatively small concave surface, which becomes manifest in the small height dimension of the lens. Nevertheless, the headlight lantern system satisfies, in accordance with the design of the pane, the requirements imposed in the various countries of the world on the dipped beam and on the main beam.
A great advantage of lanterns having a small height dimension is that the front part of automobiles can be low and hence can have a low air resistance and that the designer of the automobiles has a great freedom.
Disadvantages of the known headlight lantern system are that a comparatively expensive electronic system is required for the ignition and the operation of the gas discharge lamps, that these lamps do not instantaneously emit full light and that they can be reignited only with difficulty when they are still hot.